b2KIT

Pressure Unit Converter

Convert between PSI, bar, atm, Pascal, mmHg, and other pressure units instantly.

Tested tool guide Tested browser tools Checked August 16, 2026

What Pressure Unit Converter does, with a checked example

Tire gauges in the United States read PSI, European door stickers quote bar, weather forecasts use hectopascals, and lab work is done in pascals - the same physical pressure, four different numbers. This converter takes a value in any of the common pressure units and returns its equivalent in the others, so you can compare a reading across gauges and documents without hunting for the conversion factor. The thing most users get wrong: gauge pressure measures above the atmosphere, absolute pressure measures from a vacuum, and this tool converts the number you type without knowing which one it is.

Worked example

A concrete input and expected output from the current implementation.

Input

32 PSI

Expected output

2.206 bar, 220.6 kPa, 1655 mmHg, 2.18 atm

One PSI is defined as 6894.757 Pa, so 32 PSI is 220,632 Pa. Dividing by 100,000 Pa per bar gives 2.206 bar; dividing instead by 101,325 Pa per atm gives 2.18 atm, and by 133.322 Pa per mmHg gives 1655 mmHg. This is the value a European tire gauge would show as about 2.2 bar.

How the result is produced

1

Linear scaling through the pascal

Every unit this converter supports is a fixed multiple of the pascal, so each conversion is one multiply. PSI becomes pascals by the exact factor 6894.757 Pa, bar by 100,000 Pa, atm by 101,325 Pa. The factors are defined constants, not measurements, so the arithmetic is exact to the last digit the tool shows.

2

Gauge versus absolute

Gauge pressure counts only the pressure above the atmosphere; absolute pressure starts from a vacuum. A tire at 32 PSI gauge sits at roughly 46.7 PSI absolute, because sea-level atmosphere adds 14.696 PSI. The converter cannot see how a reading was taken, so it converts the number as typed; deciding which scale you meant is the user's job.

Good uses

  • Setting tire pressure: your gauge reads PSI but the vehicle's door sticker quotes bar or kPa, so convert the sticker value into the gauge's unit before inflating.
  • Reconciling readings between gear: dive computers log in bar, compressor and welding regulators in PSI, and barometers in mmHg or hPa; convert one figure to the unit the other device or manual uses.
  • Checking rated pressures against your equipment: converting a cylinder's rated pressure from PSI to bar before filling, or a pump spec from bar to PSI to match the fittings you own.

Limits and checks

  • Gauge versus absolute: the converter processes the number exactly as typed and cannot know how it was measured. Tire gauges read gauge pressure, so a tire at 32 PSIG is near 46.7 PSIA at sea level; mixing the two scales is off by a full atmosphere.
  • Near-duplicate units: bar and atm differ by only 1.3% and mbar equals hPa exactly, so the names get used loosely. A value quoted as atmospheres that was actually measured in bar is roughly 1.3% low, which usually does not matter and occasionally does.
  • Precision theater: the displayed digits are exact arithmetic, but the reading you typed is only as good as the instrument. A gauge marked in 1 PSI steps does not justify a result to six decimal places, and 32 PSI on one gauge can read 31 on another.

Common questions

Is 1 bar the same as 1 atm?

No. A bar is exactly 100,000 Pa and a standard atmosphere is exactly 101,325 Pa, so 1 bar equals 0.987 atm and 1 atm equals 1.013 bar. The 1.3% gap is invisible in rough work - a 2 bar reading is 1.97 atm - but it matters when comparing exact rated pressures or converting with a formula.

Why does my car's 2.2 bar tire sticker not match my PSI gauge?

It should: 2.2 bar is about 32 PSI, and both are gauge pressure, measured above atmospheric pressure. If the figures look wildly different, check whether your gauge reads absolute pressure (a few digital models can), and watch the prefix: 2.2 bar is 220 kPa, so a door sticker quoted in kPa will show three digits, not one.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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